BA Click 0.3.1

• 2026-09-11

A performance-focused release: multi-display effects under GPU contention from other apps no longer freeze, stall periodically, or fall behind the cursor.

Fixed / 修复

• Cross-display shard storm / 跨屏碎片风暴: returning to a display spawned up to maxCount shards along a garbage line from the stale cursor anchor, re-triggered on every crossing. Anchors older than the trail lifetime reset silently.
  回到某块屏幕时首次采样沿用离开前的旧锚点，一次性沿错误位置铺满碎片，每次跨屏都触发。现在过期锚点静默重置。
• Stall watchdog misfire / 看门狗误判: the watchdog treated intentionally-skipped displays (empty/idle) as stalled and force-redrew ALL overlays every 0.5s — a periodic freeze source under GPU contention. It now only reacts to a genuinely silent tick loop.
  旧看门狗把故意跳过的屏幕当停滞，每 0.5 秒强制重画全部屏幕。现在只响应真正沉默的 tick 循环。

Performance / 优化

• Sampling never blocks / 采样永不被绘制阻塞: starting a frame while the previous one is still on the GPU could block the main thread up to ~1s in currentDrawable (drawable pool exhaustion) — the trail head froze and jumped. Frames whose predecessor hasn't finished are now skipped instead: contention costs dropped frames, never a frozen trail.
  上一帧未完成时继续提交新帧可能在 currentDrawable 上阻塞主线程约 1 秒（可绘制缓冲耗尽），轨迹头部因此冻结再跳变。现在改为跳帧：争抢的代价是丢帧，而不是轨迹冻结。
• Adaptive draw pacing (DrawPacer) / 自适应隔帧绘制: when measured ticks run sustainedly over budget, every second DRAW is skipped while sampling stays full-rate — the trail head keeps hugging the cursor. Full rate restores automatically.
  tick 实测持续超预算时自动隔帧绘制（采样保持全频，轨迹头部持续贴合光标），负载恢复后自动回全速。
• Adaptive render scale / 压力下渲染分辨率自适应: sustained visible staleness (>100ms) drops overlays to 0.5× resolution (pixels ×1/4, glow content upscales invisibly); native resolution returns once staleness decays. Correctly handles Retina backing scale and enforces the target every tick (no display gets stuck at a stale scale).
  画面陈旧度持续超 100ms 时覆盖层降为 0.5× 分辨率渲染（像素 ×1/4，辉光内容拉伸无感），陈旧度消退即恢复原生；正确处理 Retina backing，且每 tick 校验，不会有屏幕卡在错误分辨率。
• Diagnostic HUD / 诊断 HUD (BA_SHOW_HUD=1): real tick/draw rates, skip breakdown (pacer / in-flight / empty), degraded flag, and drawAge — the visible-frame staleness metric.
  新增真实 tick/绘制速率、三类跳过计数、降级标志与 drawAge（画面陈旧度）。